“Jesus technically is not biologically related to David in Matthew’s gospel, even though he is called the son of David”
My response to Dr. Ehrman is below.
How would you respond to him?

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_Jesus, Interrupted: Revealing the Hidden Contradictions in the Bible (And Why We Don’t Know About Them)_ by Bart D. Ehrman (2009), 292pp. On 36, 37 …
Joseph is not Jesus’ father.
But that creates an obvious problem.
If Jesus is not a blood-relation to Joseph, why is it that Matthew and Luke trace Jesus’ bloodline precisely through Joseph?
This is a question that neither author answers: both accounts give a genealogy that can’t be the genealogy of Jesus, since his only bloodline goes through Mary, yet neither author provides her genealogy. ….
Luke explicitly indicates that the family line is that of Joseph, not Mary (Luke 1:23; also Matthew 1:16). ….
There are other problems.
In … Matthew’s genealogy …. from the Babylonian disaster to the birth of Jesus, fourteen generations (1:17).
Fourteen, fourteen, and fourteen-it is almost as if God had planned it this way. ….
The problem is that the fourteen-fourteen-fourteen schema doesn’t actually work.
If you read through the names carefully, you’ll see that in the third set of fourteen there are in fact only thirteen generations.

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Matthew 1:17 says there are 14, 14, 14 generations.
Greek manuscripts of Matthew’s genealogy mistakenly list 14, 14, 13 generations.
In Aramaic mss. of Matthew’s genealogy, with Mt 1:16’s “gbra” correctly translated as father/guardian, Matthew’s genealogy lists 14, 14, 14 generations.
Mary had a father/guardian named Joseph (plus a husband also called Joseph).
Jesus is a descendant of King David on his biological mother Mary’s side (per Mt’s genealogy), and on his step-dad Joseph’s side (per Lk’s genealogy).